WABC(PISCATAWAY, N.J.) — When New Jersey state trooper Robert Meyer woke up to knocking on his door Saturday afternoon after working the night shift, he knew it was something serious.

A Piscataway neighbor needed help after his 2-week-old granddaughter started choking, and when he saw a marked trooper car outside Meyer’s house, he knocked, New Jersey State Police said in a Facebook post.

“While she was feeding, she vomited, and it was vomit and mucus that got caught in her nose and throat,” Meyer told ABC New York City station WABC-TV.

“We attempted to pat on her back, she wasn’t doing anything.”

Knowing he had no time to lose, a shoeless Meyer darted over to his neighbor’s home, four houses away, police said on Facebook.

“I saw him flying out of the front door with no shoes on, just bed clothes on,” another neighbor, Peter Jackey, told WABC, which did not name the infant’s family.

That’s where he found the infant turning blue and struggling to breathe, police said. Using a bulb syringe the family gave him, Meyer cleared the baby’s nose and mouth of mucus, which had obstructed her breathing, police said.

“I asked if anyone had any suction that I’d be able to use to clear her airways,” Meyer told WABC. “Luckily, the dad did have one.”

Police and emergency personnel arrived not long after.

“Elizabeth suffered no serious injuries, and she is expected to make a full recovery,” according to the Facebook post. “Great job, Troop!”